but he said what he said just a few moments ago, inside this event, honoring gabe zimmerman, the government will get to the bottom of this. he's assuring americans of that. and, anderson, from being on capitol hill all day long, talking to a variety of senators, a lot of senators are expressing the same thought. they just don't know what happened in boston. they are grappling for answers like everybody else. >> yeah, it may be a while before we know. very active investigation on multiple fronts, both here, in boston, in washington, around the country, and really around the world. a lot of resources being pulled into this. jake tapper joins me now. you spoke with an er doctor who was on the scene at the end of the marathon. and lives were saved because triage areas had already been set up because it was the end of the race. >> it is really an incredible story. there were so many doctors and nurses who had volunteered. we spoke with one of them, dr. christina herndon. she works at umass memorial. she talked about the experience, her seventh boston marathon, volunteering, and she talked to us